In the manufacture of capacitor windings, a conducting sheet and an insulating sheet are wound together to produce alternating layers of conductor and insulator. Separate sheets of metal conductor and polymeric insulator or a metalized film can be used.
The capacitance of a winding can be increased by using thinner dielectric films, but it is difficult to produce thin dielectric films that are pinhole free. Pinholes in the dielectric film will result in the conductance of the charge between adjacent layers of metal foil, resulting in a loss of capacitance.